This invention relates to a waterproof fabric of the type comprising a permeable textile substrate and a water-repellent, synthetic coating firmly adhering to at least one side of said substrate.
This type of fabric has the disadvantage of not "breathing", such that the garments made therewith are repellent in both directions and prevent ventilation of the mass enveloped in said garment.
It is the object of the present invention to eliminate these disadvantages and to provide a fabric which is impermeable to water, yet permeable to air and to gases in general.
To this effect, the synthetic coating used is a thin film of coagulated polyamide having an open, asymmetrical microporous structure and comprising a first layer in direct contact with the textile substrate with large, elongated pores extending transversely to the surface of the film and issuing upon the textile substrate, and a second layer with small, open ovoid pores communicating with both the elongated pores and the surface of the coagulated polyamide film.
The film best suited to this purpose is polyamide 6 or 6/6 film. Such a structure yields a fabric which is impervious to water at atmospheric pressure and at slightly higher pressures, yet remains permeable to gases. This coating has also proved to be outstandingly resistant to abrasion and breaking.
The invention also relates to a method of fabricating a waterproof fabric, wherein a textile substrate having interstices less than 1 mm wide is taut and coated on one side with a thin film of synthetic material and the whole then treated to solidify said film.
Up to now, this type of method has not made it possible to obtain a fabric both impervious to water and permeable to gases.
It is thus another object of the invention to obviate the latter disadvantage.